Electric fuse.



R. A. LEWIS & E. C. WEISGERBER.

ELECTRIC FUSE.

APPLICATION men 020.1, I916.

1,262,683. Patented Apr. 16, 1918.

UNIT STATES are 1 r anion ELECTRIC FUSE.

Application filed December 1, 1918.

To all whom it may concern:

Be it known that we, ROBERT A. Lnwrs and EDWIN C. Winsennnnn, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, citizens of the United States, have invented or discovered certain new and useful Improvement in Electric Fuses, of which improvement the following is a specification.

The object of our invention is to provide an electric fuse in which the fusible element is removably held in a protecting casing in such a manner as to afiord and assure good electrical conductivity, and in which the fusible element, when blown, may be quickly replaced with another. A further object is to provide a simple and efiective detector for visibly indicating whether or not the fusible element has been blown.

In the accompanying sheet of drawings, which form part of our specification we have illustrated the preferred embodiment of our invention. Figure 1 is a side View of the fuse; Fig. 2 a longitudinal central sectional View taken on the line IIII, Fig. 1; Fig. 3 a transverse sectional view taken on the line IIIIII, Fig. 2; and Fig. 4 a combined side and longitudinal central sectional view of a modification of construction.

In the practice of our invention we provide the interior of the fuse casing with pairs of spring clips adapted to engage the 0pposite ends of a fusible element, and the opposite ends of the casing are closed by caps of conducting material adapted when in place to cooperate with the spring clips to afford good electrical contact with the fusible element.

Referring first to Figs. 1, 2 and 3 of the drawings, the casing 1 may be made of any suitable insulating material such as hard fiber, and is preferably in the form of a cylindrical leeve having open ends. At each end of the casing a pair of electrical conducting spring clips 2 is secured to or formed integrally with a collar 8 which is attached to the casing by means of rivets a. The members of these pairs of clips are preferably on opposite sides of the axis of the casing and their free ends face the ends of the casing in such manner as to resist an axial end thrust upon the fuse strip and to hold the fuse strip taut. While various forms of fuse strips may be used, we preferably use a flat unresilient but flexible strip 5 attached Specification of Letters Patent.

Patented Apr. 16, 1918.

Serial No. 134,414.

at its ends to enlarged contactors 6. Adjacent to the contactors tl ere are short round portions of harder metal than the strips, and the ends of the spring clips may be rooved to receive these rounded portions.

The cap for closing each end of the casing is preferably a cup-shaped ferrule 7, adapted to telescope with the casing, and provided with bayonet slots 8 to receive the outer ends of the rivets 4. The caps are of electrical conducting material and may, if desired, be provided with knife blade contacts 9. To the end that the clips may be electrically connected to the caps, the outer end of each rivet is provided with a laterally projecting shoulder 10 and beveled head 11, the space between these projecting parts being such that the wall of the cap adjacent to the bayonet slots will be pressed into firm contact with the rivets. The interior of each cap is provided with a spring 12 adapted to bear against the outer end of a fuse strip c011- tactor 6.

By such an arrangement it will be seen that each end of the fuse strip is held between three springs, which, when the fuse is installed, are electrically connected to the circuit. Two of these springs are the clips 2 which press outwardly upon the inner face of a contactor 6, and the third is the cap spring 12 which presses inwardly upon the outer face of the contactor. To refill the casin when the strip has blown, the caps are first removed from each end and the ends of the blown strip taken out. A new strip may then be inserted from one end of the casing at the sides of the spring clips and then snapped into engagement by them. The caps being again attached, the fuse is in readiness for further use.

The modified form illustrated in Fig. 4: is particularly adapted for high capacity service. In it the ends of the clips 2 are provided exterior-1y with tapered threads adapted to receive cap nuts 13 which bind the clips into firm and extensive contact with the outer ends of the fuse strip. Other wise this form is the same as that particularly shown in Fig. 2 and described above.

A further feature of our invention has to do with the provision of a detector for fuses of the general character illustrated herein. In the practice of this feature of our invention we provide a pair of shunt circuit conductors of higher electrical resistance than the fuse strip, and electrically connect one end of each of these conductors with a conducting element at one end of the casing. The other ends of tnese higher resistance conductors project through the casing, and between them there is placed a readily replaceable fusible member.

In the embodiment of the invention shown in Fig. 2 the high resistance conductors 14: are connected at one end to the collars 3, and, in the form of pins 15, project through the casing 1 near its center. Electrical continuity is established between the outer ends of the pins by means of a fusible link 16 which is preferably pasted on the face of a strip 17 of paper or other suitable material. The strip may in turn be pasted on the fuse casing, the strip being provided with an adhesive coating for this purpose.

' If desired the strip may be provided with a small powder cap 18 adapted to ignite when the link 16 is fused.

It will be understood of this detector that in the normal operation of the fuse little current flows through the shunt circuit conductors H. V hen the fuse strip 5 blows, the increased current through the link 16 will fuse it and such fusion will be indicated by strip 17 whether or not it is provided with an explosive cap 18. When the fuse is refilled a new detector strip may be readily applied to the casing in the manner already explained.

No claims are made herein to the detector described above nor to the specific form of fuse shown in Fig. a in which the cap 18 is used to tighten the spring clips upon the fusible element, these two features of invention being claimed in divisional applications. Y

According to the provision of the patent statutes we have described the principle and operation of our invention together with the fuse which we now consider to represent the best embodiment thereof. However, we desire to have it understood that within the scope of the appended claims, our invention may be practised in other forms of construction than those specifically shown and described.

We claim as our invention:

1. In an electric fuse, the combination of a casing, pairs of spring clips secured to the interior of the casing adjacent to each end thereof, the members of each pair of clips facing the end thereof adjacent to which they are attached, and a fuse strip provided with transversely disposed ends, the sides of said strip being engaged by said pairs of clips, and said clips pressing outwardly upon the inner faces of the transversely dis posed fuse strip ends whereby the strip is held taut.

2. In an electric fuse, the combination of a casing open at its opposite ends, pairs of spring clips secured to the interior of the casing adjacent to each end thereof, the members of each pair of clips being on opposite sides of the center of the casing and facing the end thereof adjacent to which they are attached, a fuse strip provided with transversely disposed ends, the sides of said strip being engaged by said pairs of clips, and said clips pressing outwardly upon the inner faces of the transversely disposed strip ends whereby the strip is held taut, and electrical conducting caps secured to the ends of the casing.

3. In an electric fuse, the combination of a casing, pairs of spring clips within the casing adjacent to each end thereof, the members of each pair of clips facing the end of the casing adjacent to which they are located, and a fuse strip provided at its opposite ends with detents engaged by said pairs of clips, said clips pressing outwardly upon said detents whereby said strip is held taut.

at. In an electric fuse, the combination of a casing open at its opposite ends, pairs of spring clips within the casing adjacent to each end thereof, the members of each pair of clips facing the end of the casing adjacent to which they are located, a fuse strip provided at its opposite ends with detents engaged by said pairs of clips, said clips pressing outwardly upon said detents whereby said strip is held taut, and electrical conducting caps secured to the ends of the casing.

In testimony whereof we have hereunto set our hands.

ROBERT A. LEWIS. EDXVIN C. VVEISGERBER. lVitnesses PAUL N. CnircrrLow, FRANCIS J. TOMASSON.

@opies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, ID. C. 

